Field of the Invention
The present invention relates to a bellows-type protective “boot” or “gaiter” for protecting the male and female elements of a transmission joint, and it also relates to a transmission joint equipped with such a protective boot.
The present invention relates more particularly to a protective boot for protecting the male element and the female element of a transmission joint, one of which elements is formed by a transmission shaft having radial arms for carrying rollers, and the other of which elements, also known as a “tulip” or as a “bowl” or “socket”, is formed by a bell housing suitable for at least partially receiving said rollers, which are suitable for being inserted into the bell housing via the open end of said bell housing, said boot, which is in the form of an elongate hollow body suitable for enabling said shaft to pass through it, having a “first” one of its ends suitable for being secured to said shaft, and having its “second” other one of its ends suitable for being positioned in overlapping and interfitting manner over the open end of the bell housing, said boot having an internal peripheral shoulder.
Description of Related Art
It is conventional to use a “constant-velocity” joint as a power transmission element for transmitting rotary drive power from a drive shaft of a vehicle to the wheels of said vehicle.
In motor vehicles, for example, between the gearbox and each wheel of the vehicle, a transmission is provided that is made up of two shafts interconnected by a mechanical transmission member that requires lubrication. Generally, the shaft coming from the gearbox is equipped with a tulip that constitutes the female element of the transmission member connecting that first shaft to the second transmission shaft. The female element is in the form of a generally three-lobed cavity. The lobes thus define recesses, each of which is, for example, designed to receive a respective roller. Each roller is carried by a male element that has three roller spindles. The male element is itself coupled to the second transmission shaft. A protective boot for protecting such a “tripod” or “spider” constant-velocity joint of the above-described type can have a cylindro-conical boot that, at one end, has a poly-lobed large base that, in the assembled state, presses against the outside surface of the tulip or bowl of the joint. The large base thus has an inside surface of shape complementary to the outside shape of the poly-lobed tulip. In the assembled state in which the boot is mounted on said tulip, a ring or collar surrounds the large base of the boot and is in the form of a circular surface that is concentric about the longitudinal axis of the boot so as to press the poly-lobed surface of said large base against the periphery of the tulip. The small base of the boot is fastened to the transmission shaft that is secured to the male element of the joint.
Joints are also known in which the male element is a shaft carrying balls for forming a ball bearing, as described in Patent EP-0 791 150. In such a joint, the boot has an internal radial shoulder formed integrally with the boot body. That shoulder forms a thrust surface preventing the balls from being dislodged from the boot during the assembly operations.
That phenomenon of it being possible for the rotary members carried by the shaft of the male element of the boot to escape can also be observed with shafts having arms for carrying rollers. However, since the rollers are suitable for coming directly into contact with said shoulder, there is a risk of said shoulder being deformed, thereby preventing the shaft having the arms for carrying the rollers from coming to a stop cleanly and immediately at the end of its assembly stroke when the rollers come into contact with said shoulder.
Finally, a protective boot of the above-mentioned type is known from Document DE-29 27 648 that constitutes the closest state of the art. In that document, the internal peripheral shoulder has an even surface in the circumferential direction and a curved profile in a radial direction so that each roller can roll freely in the circumferential direction along said shoulder without encountering any obstacles, such as recesses or projections, and, as a result, contact between the roller and the shoulder is at a point only, with, as a result, risks of the shoulder deforming.